Alone among the living hominoids, humans and chimpanzees hunt and eat mammals on a regular basis. Recent research on the hunting ecology of wild chimpanzees (Pan troglodytes) helps to reconstruct the probable foraging ecology of the earliest hominids. For both chimpanzees and traditional foraging peoples, meat composes a small portion of the diet, and foraging decisions based on nutritional cost-benefit tradeoffs are made continually. Various hypotheses have been advanced to explain why chimpanzees hunt; current data suggest that in addition to nutritional bases of hunting, political and reproductive benefits may be important influences.